Look at ketamine vs esketamine, for example: "Why isn’t ketamine an approved depression treatment, then? It comes down to profits. Ketamine’s patent expired in 2002, meaning that further studies into the drug would not bring any financial returns to the companies funding them." [1]
I think it would make sense that there are also natural remedies that may be available, and cheap for consumers, but simply aren't considered because they would not be profitable. It's not worth it for them to look into these natural remedies if they can't put a patent on them and make money. Big Pharma, being primarily for profit, would even have an incentive to discredit these natural remedies, as it could harm their business.
[1] https://qz.com/1889308/why-isnt-ketamine-approved-as-an-anti...